DG412DY Integrated Circuits (ICs)

DG412DY is a low capacitance single pole four throw (SP4T) monolithic CMOS switch that is designed for RF and general purpose analog/logic applications. This switch requireslow supply voltages ranging from 0V to 10V, has extremely low power consumption, an excellent off isolation of greater than 70 dB at 1 MHz, low charge injection of ≤ 2 pC, and itsenable/disable logic is TTL/CMOS compatible. DG412DY is a member of Maxim\'s family of high-performance CMOS switches.

The device is constructed with P-channel MOSFETs (2) and N-channel MOSFETs (2) per switch, configured to form a low resistance single throw switch, and a high resistance single throw switch back-to-back. This configuration results in excellent off-isolation, low charge injection and low residual signal leakage.

This application note discusses the principle of operation of the DG412DY switch, the recommended value of several external components, as well as application examples.

Working principle

The DG412DY switch consists of four single pole, four-throw (SP4T) switches, each constructed with two N-channel MOSFETs, and two P-Channel MOSFETs. Figure 1 shows a schematic diagram of one switch. When enabled with E1 or E2, digital signals control the states of S1, S2, S3, and S4. During a valid switch state, the low resistance (RDS1 or RDS2) MOSFETs are off and the high resistance (RDS3 or RDS4) MOSFETs are on (see Figure 1).

When the input logic high indicating an operate state and the low indicating a return state is applied to E1 and E2 inputs, S1 and S2 switch to a high and low resistance state, respectively. This is a typical configuration when driving a load. For general analog signal switching, the DG412DY switches, however, in an opposite direction to what is accomplished by E1 and E2 of a typical switch. When the inputs E1 and E2 are low, S1 and S2 switch to low and high resistance states, respectively.

In some cases, it may be desirable to connect two DG412DYs in parallel for applications demanding fast switching speeds or higher off isolation characteristics. Each switch is independent of the other. Figure 2 shows the schematic connection of two DG412DY\'s in parallel. Note that the state of one DG412DY has no effect on the state of the other.

Example applications

The DG412DY is a versatile switch and can be used in a wide variety of applications such as RF, microwave, and analog/logic switching. It has a wide variety of functions such as switching, mixing, attenuation, gain control, phase shift and modulation, etc. Below are some example applications.

RF Switching

The DG412DY is used for RF signal routing and antenna switching. It can be used for applications such as cellular phone, CATV, and wireless communication. It can switch from high frequency to low frequency in the range from DC to 2GHz. The DG412DY is ideal for this application because of its low power consumption, small package size, and low on capacitance.

Multiplexer

The DG412DY is ideal for use as a multiplexer because of its excellent off isolation and low charge injection capability. It is suitable for switching between two or more analog or digital signals such as microphone input signals.

Attenuator

The DG412DY can be used as an attenuator in applications such as audio systems and radio receivers. It is suitable for attenuating wide-band signals from DC to 2 GHz with a low loss and fast switching speed.

Conclusion

The DG412DY is a low capacitance single pole four throw (SP4T) monolithic CMOS switch that is designed for RF and general purpose analog/logic applications. It has low power consumption, an excellent off isolation of greater than 70 dB at 1 MHz, and its enable/disable logic is TTL/CMOS compatible. It can be used for RF signal routing and antenna switching, as a multiplexer, and as an attenuator.