Low impedance gate drive to the 2N3970 analog switch for both on and off drive conditions is provided by this commutator. By producing a low ac impedance for off drive and high ac impedance for on drive to the 2N3970, this commutator circuit can close enough to the ideal gate drive conditions for high frequency signal handling. We use LH0005 as a megahertz signals amplifier.

Here’s the circuit diagram:

[Source: National Semiconductor Application Note]

This is circuit of  DTL-TTL controlled buffered analog Switch. Due to its low lowleakage and 25ohm rOn, this circuit uses 2N4860 JFET. As a voltage buffer, this circuit uses LM 102. Here is the circuit :

A dual trace oscilloscope chopper can adapt this circuit. Adequate  switch drive controlled DTL-TTL logic levels are generated by the DM7800 monolithic I.C. [Source: National Semiconductor Application Note]

This application note explains about aspects of data acquisition system design. The main topic is divided into 7 section :

• Signal processing challenges
• Common ADC architectures
• System requirements
• Selecting the data converter
• Interfacing the data converter
• Signal conditioning op amp selection
• Issues of board layout

The challenges of signal processing is presented in signal processing challenges section. Common ADC architectures section describe about successive approximation register (SAR), dual-slope, sigma-delta, flash, semi-flash and pipeline. System requirements and how to select the data converter are presented in system requirements and selecting the data converter section. Interfacing the data converter section explains conventional digital receiver. How to select the signal conditioning op amp is presented in signal conditioning op amp selection section. And issues of board layout section explain about issues of board layout.

Download/view the application note

This analog applications journal presents about a methodology of interfacing serial A-to-D converters to DSPs. The theory about serial analog-to digital converters, standard serial interface, serial port general operation are presented in detail after introduction. The main topic is divided into 9 sections :

• Introduction
• Serial analog-to-digital converters
• Standard serial interface
• Serial port general operation
• Serial port configuration
• Transmit and receive operations in burst mode
• Interfacing to sequential ADCs
• Interfacing to “on-the-fly” ADCs
• C-callable interface routines

The detail about serial analog-to-digital converters is presented in section serial analog-to-digital converters. The section standard serial interface describes about interface of standard serial. Serial port general operation and its configuration are presented in detail under section serial port general operation and serial port configuration. The section transmit and receive operations in burst mode presents how the operation of transmit and receive work in burs mode. Interfacing to sequential ADCs and “on-the fly” ADCs are described in detail in section interfacing to sequential ADCs and Interfacing to “on-the-fly” ADCs. C-callable interface routines section describes about C-callable interface routines.

Download/view the application note.