Patent ID: 8112236
Filing Date: 2012-02-07
Classification: G01R

Abstract:
1. A device capable of receiving one or more digital input stimulus signals and accurately measuring an open-loop gain of an operational amplifier under test (OPAUT), the device comprising: a digital charge converter (DCC) comprising one or more sampling capacitors and a plurality of switches controlled by a plurality of control signals, for outputting a charge signal based on at least one of the digital input stimulus signals and a plurality of reference signals; a charge integrator including the OPAUT having a positive input and a negative input and at least one integrating capacitor, coupled to receive the charge signal and at least one of the reference signals, for outputting an integration signal by amplifying a potential difference across the positive input and the negative input of the OPAUT; an analog to digital (A/D) converter coupled to receive the integration signal and at least one of the reference signals, for outputting a digital feedback signal which comprises a maximum logic state and a minimum logic state; a control logic circuit coupled to receive at least one clock signal (CLK), the digital feedback signal and at least one of the digital input stimulus signals, for generating the control signals to control the switches of the DCC and the A/D converter, in which each of the digital input stimulus signals is a Sigma-Delta modulated digital stimulus bit-stream which comprises a first logic state and a second logic state, and the clock signal is utilized to generate at least two non-overlap clock phases including a first clock phase and a second clock phase; and an arithmetic logic unit (ALU) coupled to receive the digital input stimulus signals and the digital feedback signal, for computing an open-loop gain of the OPAUT.