Dc frequency crystal oscillator - Allicdata Electronics

Related Categories

1 2 3 4 5 >

Allicdata Part#	Mft.Part#	Company	Spec.	QTY.	Pricing(USD)
1465-1382-2-ND	MASWSS0166TR-30 00	M/A-Com Technology Solutions	View more Packaging: Tape & Reel (TR) Part Status: Active RF Type: Cellular, GSM, DCS, PCS Topology: Reflective Circuit: SPDT Frequency Range: DC ~ 3GHz Isolation: 12dB Insertion Loss: 0.55dB Test Frequency: 3GHz P1dB: 27dBm IIP3: 55dBm Impedance: 50 Ohm Operating Temperature: -40C ~ 85C Package / Case: 6-TSSOP, SC-88, SOT-363 Supplier Device Package: SOT-363	6000 Order	3000+: $0.2558 6000+: $0.243 15000+: $0.2339
863-1236-2-ND	AS176-59LF	Skyworks Solutions Inc.	View more Packaging: Tape & Reel (TR) Part Status: Obsolete RF Type: Cellular, 3G, DCS, ISM, PCS Topology: Reflective Circuit: SPDT Frequency Range: 300kHz ~ 3GHz Isolation: 27dB Insertion Loss: 0.9dB Test Frequency: 3GHz IIP3: 45dBm Impedance: 50 Ohm Voltage - Supply: 3V, 5V Operating Temperature: -40C ~ 85C Package / Case: 8-TSSOP, 8-MSOP (0.118", 3.00mm Width) Supplier Device Package: 8-MSOP	1000 Order	--
1465-1373-2-ND	MASWSS0115TR-30 00	M/A-Com Technology Solutions	View more Packaging: Tape & Reel (TR) Part Status: Active RF Type: GSM, DCS, PCS Topology: Reflective Circuit: SPDT Frequency Range: DC ~ 3GHz Isolation: 22dB Insertion Loss: 0.3dB Test Frequency: 3GHz P1dB: 25dBm Impedance: 50 Ohm Operating Temperature: -40C ~ 85C Package / Case: 6-TSSOP, SC-88, SOT-363 Supplier Device Package: SC-70-6 (SOT-363)	195000 Order	--
1465-1391-2-ND	MASWSS0201TR	M/A-Com Technology Solutions	View more Packaging: Tape & Reel (TR) Part Status: Active RF Type: CATV Topology: Absorptive Circuit: SPDT Frequency Range: DC ~ 2.5GHz Isolation: 43dB Insertion Loss: 1.5dB Test Frequency: 2GHz IIP3: 44dBm Impedance: 75 Ohm Operating Temperature: -40C ~ 85C Package / Case: 12-VFQFN Exposed Pad Supplier Device Package: 12-PQFN (3x3)	1000 Order	--
1465-1360-2-ND	MASW-007935-TR3 000	M/A-Com Technology Solutions	View more Packaging: Tape & Reel (TR) Part Status: Active RF Type: CDMA, GSM Topology: Absorptive Circuit: SPDT Frequency Range: DC ~ 3GHz Isolation: 22dB Insertion Loss: 1.1dB Test Frequency: 3GHz Impedance: 50 Ohm Operating Temperature: -40C ~ 85C Package / Case: SOT-23-6 Supplier Device Package: SOT-26	3000 Order	3000+: $0.2999 6000+: $0.2849 15000+: $0.2742
1465-1385-2-ND	MASWSS0176TR-30 00	M/A-Com Technology Solutions	View more Packaging: Tape & Reel (TR) Part Status: Active RF Type: GSM, DCS, PCS Topology: Reflective Circuit: SPDT Frequency Range: 50MHz ~ 3GHz Isolation: 21dB Insertion Loss: 0.35dB Test Frequency: 3GHz P1dB: 21dBm Impedance: 50 Ohm Operating Temperature: -40C ~ 85C Package / Case: SOT-23-6 Supplier Device Package: SOT-26	1000 Order	3000+: $0.2646 6000+: $0.2514 15000+: $0.2419
1465-1364-2-ND	MASW-008566-TR3 000	M/A-Com Technology Solutions	View more Packaging: Tape & Reel (TR) Part Status: Active RF Type: General Purpose Topology: Reflective Circuit: SP4T Frequency Range: DC ~ 3GHz Isolation: 18.5dB Insertion Loss: 1dB Test Frequency: 3GHz Impedance: 50 Ohm Operating Temperature: -40C ~ 85C Package / Case: 16-VQFN Exposed Pad Supplier Device Package: 16-PQFN (4x4)	6000 Order	3000+: $0.7484 6000+: $0.7207
1465-1359-2-ND	MASW-007921-TR3 000	M/A-Com Technology Solutions	View more Packaging: Tape & Reel (TR) Part Status: Active RF Type: WiMax, WLAN Topology: Reflective Circuit: SPDT Frequency Range: DC ~ 7GHz Isolation: 30dB Insertion Loss: 1.2dB Test Frequency: 5.8GHz Impedance: 50 Ohm Operating Temperature: -40C ~ 85C Package / Case: 8-VFDFN Exposed Pad Supplier Device Package: 8-PDFN (2x2)	3000 Order	--
1465-1362-2-ND	MASW-008322-TR1 000	M/A-Com Technology Solutions	View more Packaging: Tape & Reel (TR) Part Status: Active RF Type: General Purpose Topology: Reflective Circuit: SPDT Frequency Range: DC ~ 20GHz Isolation: 40dB Insertion Loss: 1.9dB Test Frequency: 20GHz P1dB: 30dBm IIP3: 48dBm Impedance: 50 Ohm Operating Temperature: -40C ~ 85C Package / Case: 24-VFQFN Exposed Pad Supplier Device Package: 24-PQFN (4x4)	1000 Order	1000+: $8.3623
1465-1374-2-ND	MASWSS0129TR-30 00	M/A-Com Technology Solutions	View more Packaging: Tape & Reel (TR) Part Status: Active RF Type: 802.11a/b/g Topology: Reflective Circuit: DPDT Frequency Range: DC ~ 6GHz Isolation: 30dB Insertion Loss: 1dB Test Frequency: 6GHz P1dB: 31dBm Impedance: 50 Ohm Operating Temperature: -40C ~ 85C Package / Case: 12-VFQFN Exposed Pad Supplier Device Package: 12-PQFN (3x3)	1000 Order	1+: $0
1465-1358-2-ND	MASW-007813-TR3 000	M/A-Com Technology Solutions	View more Packaging: Tape & Reel (TR) Part Status: Active RF Type: CDMA, GSM Topology: Reflective Circuit: SP4T Frequency Range: DC ~ 3GHz Isolation: 23dB Insertion Loss: 1dB Test Frequency: 3GHz Impedance: 50 Ohm Operating Temperature: -40C ~ 85C Package / Case: 16-WFQFN Exposed Pad Supplier Device Package: 16-PQFN (3x3)	1000 Order	--
1127-2928-ND	HMC284AMS8GE	Analog Devices Inc.	View more Packaging: Cut Strip Part Status: Active RF Type: Cellular, ISM, PCS Topology: Absorptive Circuit: SPDT Frequency Range: DC ~ 3.5GHz Isolation: 40dB Insertion Loss: 0.7dB Test Frequency: 3.5GHz P1dB: 29dBm IIP3: 50dBm (min) Impedance: 50 Ohm Operating Temperature: -40C ~ 85C Package / Case: 8-TSSOP, 8-MSOP (0.118", 3.00mm Width) Exposed Pad Supplier Device Package: 8-MSOPG Base Part Number: HMC284	2521 Order	--
FMS2016-005-ND	FMS2016-005	RFMD	View more Packaging: Bulk Part Status: Obsolete RF Type: Cellular, GSM, DCS, PCS Topology: Reflective Circuit: SP4T Frequency Range: 500MHz ~ 2.5GHz Isolation: 32dB Insertion Loss: 0.65dB Test Frequency: 2GHz IIP3: 66dBm Impedance: 50 Ohm Operating Temperature: -40C ~ 100C Package / Case: 12-VFQFN Supplier Device Package: 12-QFN (3x3)	1000 Order	500+: $1.9661
1127-3512-ND	HMC284AMS8G	Analog Devices Inc.	View more Packaging: Cut Strip Part Status: Obsolete RF Type: Cellular, ISM, PCS Topology: Absorptive Circuit: SPDT Frequency Range: DC ~ 3.5GHz Isolation: 40dB Insertion Loss: 0.7dB Test Frequency: 3.5GHz P1dB: 29dBm IIP3: 50dBm (min) Impedance: 50 Ohm Operating Temperature: -40C ~ 85C Package / Case: 8-TSSOP, 8-MSOP (0.118", 3.00mm Width) Exposed Pad Supplier Device Package: 8-MSOPG Base Part Number: HMC284	1000 Order	1+: $0
1465-1355-2-ND	MASW-007221-TR3 000	M/A-Com Technology Solutions	View more Packaging: Tape & Reel (TR) Part Status: Active RF Type: Cellular, CDMA, GSM Topology: Reflective Circuit: SPDT Frequency Range: DC ~ 3GHz Isolation: 12dB Insertion Loss: 0.56dB Test Frequency: 3GHz P1dB: 27dBm Impedance: 50 Ohm Voltage - Supply: 2.3 V ~ 8 V Operating Temperature: -40C ~ 85C Package / Case: 6-TSSOP, SC-88, SOT-363 Supplier Device Package: SC-70-6 (SOT-363)	6000 Order	3000+: $0.2381 6000+: $0.2262 15000+: $0.2177
1465-1392-2-ND	MASWSS0202TR-30 00	M/A-Com Technology Solutions	View more Packaging: Tape & Reel (TR) Part Status: Active RF Type: 802.11a/b/g Topology: Reflective Circuit: SPDT Frequency Range: DC ~ 6GHz Isolation: 25dB Insertion Loss: 0.75dB Test Frequency: 6GHz P1dB: 35dBm IIP3: 51dBm Impedance: 50 Ohm Operating Temperature: -40C ~ 85C Package / Case: 12-VFQFN Exposed Pad Supplier Device Package: 12-PQFN (3x3)	1000 Order	--
1127-1317-2-ND	HMC284AMS8GETR	Analog Devices Inc.	View more Packaging: Tape & Reel (TR) Part Status: Active RF Type: Cellular, ISM, PCS Topology: Absorptive Circuit: SPDT Frequency Range: DC ~ 3.5GHz Isolation: 40dB Insertion Loss: 0.7dB Test Frequency: 3.5GHz P1dB: 29dBm IIP3: 50dBm (min) Impedance: 50 Ohm Operating Temperature: -40C ~ 85C Package / Case: 8-TSSOP, 8-MSOP (0.118", 3.00mm Width) Exposed Pad Supplier Device Package: 8-MSOPG Base Part Number: HMC284	500 Order	--
RF1603ASQ-ND	RF1603ASQ	RFMD	View more Packaging: Tray Part Status: Discontinued at Digi-Key RF Type: CDMA, GSM, EDGE, W-CDMA Topology: Reflective Circuit: SP3T Frequency Range: DC ~ 2.5GHz Isolation: 28dB Insertion Loss: 0.7dB Test Frequency: 3.5GHz IIP3: 73dBm Features: DC Blocked Impedance: 50 Ohm Voltage - Supply: 2.2 V ~ 2.7 V Operating Temperature: -30C ~ 85C Package / Case: 12-UFQFN Exposed Pad Supplier Device Package: 12-QFN (2.5x2.5)	1000 Order	25+: $1.071
1465-1378-2-ND	MASWSS0144TR-30 00	M/A-Com Technology Solutions	View more Packaging: Tape & Reel (TR) Part Status: Active RF Type: Cellular, CDMA, GPS, PCS Topology: Reflective Circuit: SP3T Frequency Range: DC ~ 3GHz Isolation: 19dB Insertion Loss: 0.75dB Test Frequency: 3GHz Impedance: 50 Ohm Operating Temperature: -40C ~ 85C Package / Case: 12-VFQFN Exposed Pad Supplier Device Package: 12-PQFN (3x3)	1000 Order	3000+: $0.4593 6000+: $0.4423
ARV13A4HQ-ND	ARV13A4HQ	Panasonic Electric Works	View more Packaging: Bulk Part Status: Active RF Type: General Purpose Topology: Reflective Circuit: SPDT Frequency Range: DC ~ 8GHz Isolation: 70dB (min) Insertion Loss: 0.3dB (max) Test Frequency: 8GHz Impedance: 50 Ohm Voltage - Supply: 4.5V Operating Temperature: -55C ~ 85C Package / Case: Module, SMA Connectors Supplier Device Package: Module	1000 Order	5+: $424.521
ARD72024-ND	ARD72024	Panasonic Electric Works	View more Packaging: Bulk Part Status: Active RF Type: General Purpose Topology: Reflective Circuit: SPDT Frequency Range: DC ~ 6GHz Isolation: 70dB (min) Insertion Loss: 0.3dB Test Frequency: 8GHz Impedance: 50 Ohm Voltage - Supply: 24V Operating Temperature: -55C ~ 85C Package / Case: Module, Pin Contacts	1000 Order	1+: $264.524
HMC231G7-ND	HMC231G7	Analog Devices Inc.	View more Packaging: Cut Strip Part Status: Obsolete RF Type: General Purpose Circuit: SPDT Frequency Range: DC ~ 6GHz Isolation: 48dB Insertion Loss: 1.4dB Test Frequency: 4GHz P1dB: 27dBm IIP3: 49dBm Impedance: 50 Ohm Voltage - Supply: 5V Operating Temperature: -40C ~ 85C Package / Case: 7-SMD, Gull Wing Supplier Device Package: 7-SMD Base Part Number: HMC231	1000 Order	1+: $0
1465-1119-ND	SW-313-PIN	M/A-Com Technology Solutions	View more Packaging: Bulk Part Status: Active RF Type: General Purpose Topology: Absorptive Circuit: SPDT Frequency Range: DC ~ 3GHz Isolation: 35dB (min) Test Frequency: 3GHz P1dB: 30dBm Impedance: 50 Ohm Operating Temperature: -55C ~ 125C Package / Case: CR-9 Supplier Device Package: CR-9	45 Order	1+: $85.2831 10+: $79.7111 25+: $76.9244
HMC253LC4TR-R5- ND	HMC253LC4TR-R5	Analog Devices Inc.	View more Packaging: Tape & Reel (TR) Part Status: Obsolete RF Type: Cellular, CATV Topology: Absorptive Circuit: SP8T Frequency Range: DC ~ 3.5GHz Isolation: 35dB Insertion Loss: 1.3dB Test Frequency: 3.5GHz IIP3: 43dBm Impedance: 50 Ohm Voltage - Supply: 4.5 V ~ 5.5 V Operating Temperature: -40C ~ 85C Package / Case: 24-TFCQFN Exposed Pad Supplier Device Package: 24-CSMT (4x4) Base Part Number: HMC253	1000 Order	1+: $0
1046-1024-2-ND	4245-52	pSemi	View more Series: UltraCMOS Packaging: Tape & Reel (TR) Part Status: Active RF Type: General Purpose Topology: Reflective Circuit: SPDT Frequency Range: DC ~ 4GHz Isolation: 32dB Insertion Loss: 0.7dB Test Frequency: 2GHz P1dB: 27dBm IIP3: 45dBm Features: Single Line Control Impedance: 50 Ohm Voltage - Supply: 2.7 V ~ 3.3 V Operating Temperature: -40C ~ 85C Package / Case: 6-VDFN Exposed Pad Supplier Device Package: 6-DFN (3x3)	30000 Order	3000+: $0.7749 6000+: $0.7056
ARD12024-ND	ARD12024	Panasonic Electric Works	View more Packaging: Bulk Part Status: Active RF Type: General Purpose Topology: Reflective Circuit: SPDT Frequency Range: DC ~ 18GHz Isolation: 60dB (min) Insertion Loss: 0.5dB (max) Test Frequency: 18GHz Impedance: 50 Ohm Voltage - Supply: 24V Operating Temperature: -55C ~ 85C Package / Case: Module, Pin Contacts	1000 Order	10+: $281.22
ARV13A12Q-ND	ARV13A12Q	Panasonic Electric Works	View more Packaging: Bulk Part Status: Active RF Type: General Purpose Topology: Reflective Circuit: SPDT Frequency Range: DC ~ 8GHz Isolation: 70dB (min) Insertion Loss: 0.3dB (max) Test Frequency: 8GHz Impedance: 50 Ohm Voltage - Supply: 12V Operating Temperature: -55C ~ 85C Package / Case: Module, SMA Connectors Supplier Device Package: Module	1000 Order	5+: $471.687
HMC347LP3TR-ND	HMC347LP3TR	Analog Devices Inc.	View more Packaging: Tape & Reel (TR) Part Status: Obsolete RF Type: General Purpose Topology: Absorptive Circuit: SPDT Frequency Range: DC ~ 14GHz Isolation: 38dB Insertion Loss: 1.9dB Test Frequency: 14GHz P1dB: 23dBm IIP3: 43dBm Impedance: 50 Ohm Operating Temperature: -55C ~ 85C Package / Case: 16-VFQFN Exposed Pad Supplier Device Package: 16-QFN (3x3) Base Part Number: HMC347	1000 Order	1+: $0
HMC253QS24E-ND	HMC253QS24E	Analog Devices Inc.	View more Packaging: Cut Strip Part Status: Obsolete RF Type: General Purpose Topology: Absorptive Circuit: SP8T Frequency Range: DC ~ 2.5GHz Isolation: 28dB Insertion Loss: 1.8dB Test Frequency: 2.5GHz P1dB: 23dBm IIP3: 43dBm Impedance: 50 Ohm Voltage - Supply: 5V Operating Temperature: -40C ~ 85C Package / Case: 24-SSOP (0.154", 3.90mm Width) Supplier Device Package: 24-QSOP Base Part Number: HMC253	1000 Order	1+: $0
PE42552MLIB-ND	PE42552MLIB	pSemi	View more Series: UltraCMOS, HaRP Packaging: Cut Strip Part Status: Obsolete RF Type: General Purpose Topology: Absorptive Circuit: SPDT Frequency Range: DC ~ 7.5GHz Isolation: 28dB Insertion Loss: 1dB Test Frequency: 7.5GHz P1dB: 34dBm IIP3: 65dBm Impedance: 50 Ohm Voltage - Supply: 3 V ~ 3.6 V Operating Temperature: -40C ~ 85C Package / Case: 16-WFQFN Exposed Pad Supplier Device Package: 16-QFN (3x3)	1000 Order	--
1465-1366-2-ND	MASW-008955-TR1 000	M/A-Com Technology Solutions	View more Packaging: Tape & Reel (TR) Part Status: Active RF Type: Bluetooth, WLAN Topology: Reflective Circuit: SP3T Frequency Range: DC ~ 3.5GHz Isolation: 20dB Insertion Loss: 0.6dB Test Frequency: 2.45GHz P1dB: 36dBm Impedance: 50 Ohm Operating Temperature: -40C ~ 85C Package / Case: 8-VFDFN Exposed Pad Supplier Device Package: 8-PDFN (2x2)	1000 Order	1000+: $0.2646 2000+: $0.247 5000+: $0.2346 10000+: $0.2258 25000+: $0.2187
255-6090-ND	ARD15105Q	Panasonic Electric Works	View more Packaging: Bulk Part Status: Active RF Type: General Purpose Topology: Reflective Circuit: SPDT Frequency Range: DC ~ 18GHz Isolation: 60dB (min) Insertion Loss: 0.5dB (max) Test Frequency: 18GHz Impedance: 50 Ohm Voltage - Supply: 5V Operating Temperature: -55C ~ 85C Package / Case: Module, Pin Contacts	1 Order	1+: $352.157 10+: $339.115
ARV10N4H-ND	ARV10N4H	Panasonic Electric Works	View more Packaging: Bulk Part Status: Active RF Type: General Purpose Topology: Reflective Circuit: SPDT Frequency Range: DC ~ 8GHz Isolation: 60dB (min) Insertion Loss: 0.4dB (max) Test Frequency: 8GHz Impedance: 50 Ohm Voltage - Supply: 4.5V Operating Temperature: -55C ~ 85C Package / Case: Module, Pin Contacts	1000 Order	5+: $424.527
ARV22A24Q-ND	ARV22A24Q	Panasonic Electric Works	View more Packaging: Bulk Part Status: Active RF Type: General Purpose Topology: Reflective Circuit: SPDT Frequency Range: DC ~ 18GHz Isolation: 60dB (min) Insertion Loss: 0.7dB (max) Test Frequency: 18GHz Impedance: 50 Ohm Voltage - Supply: 24V Operating Temperature: -55C ~ 85C Package / Case: Module, SMA Connectors Supplier Device Package: Module	1000 Order	5+: $0.63
1046-1039-2-ND	PE42552MLIB-Z	pSemi	View more Series: UltraCMOS, HaRP Packaging: Tape & Reel (TR) Part Status: Obsolete RF Type: General Purpose Topology: Absorptive Circuit: SPDT Frequency Range: DC ~ 7.5GHz Isolation: 28dB Insertion Loss: 1dB Test Frequency: 7.5GHz P1dB: 34dBm IIP3: 65dBm Impedance: 50 Ohm Voltage - Supply: 3 V ~ 3.6 V Operating Temperature: -40C ~ 85C Package / Case: 16-WFQFN Exposed Pad Supplier Device Package: 16-QFN (3x3)	1000 Order	--
1127-1060-2-ND	HMC595ETR	Analog Devices Inc.	View more Packaging: Tape & Reel (TR) Part Status: Obsolete RF Type: General Purpose Topology: Reflective Circuit: SPDT Frequency Range: DC ~ 3GHz Isolation: 18dB Insertion Loss: 0.5dB Test Frequency: 3GHz P1dB: 39dBm IIP3: 65dBm Impedance: 50 Ohm Operating Temperature: -40C ~ 85C Package / Case: SOT-23-6 Supplier Device Package: SOT-26 Base Part Number: HMC595	1000 Order	--
HMC245QS16-ND	HMC245QS16	Analog Devices Inc.	View more Packaging: Bulk Part Status: Obsolete RF Type: General Purpose Topology: Absorptive Circuit: SP3T Frequency Range: DC ~ 3.5GHz Isolation: 30dB Insertion Loss: 0.7dB Test Frequency: 3.5GHz P1dB: 25dBm IIP3: 44dBm Impedance: 50 Ohm Voltage - Supply: 5V Operating Temperature: -40C ~ 85C Package / Case: 16-SSOP (0.154", 3.90mm Width) Supplier Device Package: 16-QSOP Base Part Number: HMC245	1000 Order	--
HMC641LP4E-ND	HMC641LP4E	Analog Devices Inc.	View more Packaging: Cut Strip Part Status: Obsolete RF Type: General Purpose Topology: Absorptive Circuit: SP4T Frequency Range: DC ~ 20GHz Isolation: 40dB Insertion Loss: 3dB Test Frequency: 20GHz P1dB: 22dBm IIP3: 38dBm Impedance: 50 Ohm Operating Temperature: -40C ~ 85C Package / Case: 24-VFQFN Exposed Pad Supplier Device Package: 24-SMT (4x4) Base Part Number: HMC641	1000 Order	1+: $0
ARV13N4HQ-ND	ARV13N4HQ	Panasonic Electric Works	View more Packaging: Bulk Part Status: Active RF Type: General Purpose Topology: Reflective Circuit: SPDT Frequency Range: DC ~ 8GHz Isolation: 60dB (min) Insertion Loss: 0.4dB (max) Test Frequency: 8GHz Impedance: 50 Ohm Voltage - Supply: 4.5V Operating Temperature: -55C ~ 85C Package / Case: Module, Pin Contacts	1000 Order	5+: $455.962
ARV23A4HQ-ND	ARV23A4HQ	Panasonic Electric Works	View more Packaging: Bulk Part Status: Active RF Type: General Purpose Topology: Reflective Circuit: SPDT Frequency Range: DC ~ 18GHz Isolation: 60dB (min) Insertion Loss: 0.7dB (max) Test Frequency: 18GHz Impedance: 50 Ohm Voltage - Supply: 4.5V Operating Temperature: -55C ~ 85C Package / Case: Module, SMA Connectors Supplier Device Package: Module	1000 Order	5+: $550.302

1 2 3 4 5 >

Hot Searches: dc frequency crystal oscillator 5 volt dc frequency crystal oscillator crystal oscillator frequency crystal oscillator frequency range crystal oscillator frequency divider low frequency crystal oscillator crystal oscillator frequency measurement crystal oscillator frequency formula quartz crystal oscillator frequency crystal oscillator frequency pulling frequency crystal oscillator crystal oscillator counter frequency crystal oscillator in the base frequency crystal oscillator frequency counter crystal oscillator computer frequency carrier frequency crystal oscillator frequency range of crystal oscillator variable frequency crystal oscillator tune crystal oscillator frequency crystal oscillator frequency multiplier

Search Result:dc frequency crystal oscillator

Related Categories