Diode Bridge Tristate Measurement Circuit
Original Publication Date: 1987-Mar-01
Included in the Prior Art Database: 2005-Feb-01
The state of a diode bridge circuit normally used as a programmable dynamic current load for a device under test is monitored with a differential amplifier, thus providing detection of tristate conditions of the device. Fig. 1 is a circuit diagram wherein Vin is a voltage supplied by a device under test. Vref is a tester-programmed voltage level normally between a high (One state) of Vin and a low (Zero state) of Vin. I1 and I2 are current generators programmed by the tester. +V and -V are compliance voltages for I1 and I2, respectively. When Vin is more positive than Vref, current generator I2 draws a programmed value of current from the device under test and I1 supplies current into Vref.