Apparatus for accurately measuring open circuit gain of amplifier by utilizing digital excitation signal

Abstract

The invention relates to a device for accurately measuring open circuit gain of an amplifier by using a digital excitation signal, wherein, a digital charge converter and a charge integrator are composed of a switch, a sampling capacitor, an integrating capacitor, a single-ended output or differential output operational amplifier to be tested and the like. The digital charge converter, the charge integrator and an analog / digital converter are controlled by a control signal generated by a control logic circuit to constitute a first-order trigonometric integral modulator capable of receiving the digital excitation signal, an arithmetic logic unit calculates the open circuit gain according to digital output. Or when a digital mode signal received by the control logic circuit is a test mode, the sampling capacitor, the integrating capacitor, the operational amplifier to be tested, the analog / digital converter and the switch are controlled by a plurality of control signals generated by the control logic circuit to reconstitute the first-order trigonometric integral modulator capable of receiving the digital input excitation signal, the open circuit gain is calculated by the arithmetic logic unit.

Description

technical field [0001] 本发明涉及一种可准确测量放大器开路增益的装置,特别地是,本发明涉及一种可接收数字激发信号并可准确测量放大器开路增益的装置。 Background technique [0002] 大多数的混合信号电路的功能及准确性皆相当依赖设置于其中的运算放大器的开路增益。然而,制程变异会严重影响运算放大器的开路增益,即便使用集成电路分析仿真程序(SimulationProgram with Integrated Circuit Emphasis,SPICE)进行电路仿真,仍不能通过其模拟结果精确得知所制作出的运算放大器的真实开路增益如何。因此,准确测量运算放大器增益对于诊断雏形电路是否符合产品设计规格,便显得相当重要。 [0003] 传统上,开路增益的测量需使用昂贵的网络分析仪及繁冗的测试设定,现今系统单芯片(system on chip,SOC)集成电路中经常整合数十个运算放大器于单一芯片之中,而该嵌入式(Embedded)运算放大器通常无法驱动沉重的芯片外负载,致使无法使用传统测试法来测试此种运算放大器的开路增益。此外,有限的观察接脚使得测量嵌入式运算放大器的增益变得更加困难且昂贵。 [0004] 参照G.Giustolisi及G.Palumbo在2002年1月IEEE Trans.OnCircuits and Systems期刊中所揭露的一种测试反馈放大器的开路增益因子的测试方法,此测试方法需要极耗成本的网络分析仪来测量反馈放大器的相位及振幅响应,故此方法不适用于测量SOC内的待测运算放大器,原因在于待测运算放大器的驱动能力不足而且芯片的接脚有限,此外,该方法并假设待测运算放大器的转移函数(Transfer function)仅有两个主要极点(dominant poles),此为不当的假设,若待测运算放大器的主要极点超过两个,则会导致显著的测量误差。 [0005] 另参照K.Arabi及B.Kaminska在1998年4月于IEEE JS SC期刊所发表之“Design for Testability of Embedded Integrated OperationalAmplifiers”论文中所揭露的一种用以测量嵌入式积体运算放大器的设计,此设计系通过运算放大器及辅助电阻、电容所构成的...

AI Technical Summary

Problems solved by technology

Since the input part of the known delta-sigma modulator must be an analog signal as input, but the analog signal is not easy to control accurately and is more easily affected by test settings and environmental noise

To use analog signals for gain error testing, it is necessary to use an analog signal source that can be accurately controlled. This kind of high-quality signal source can only be provided by high-cost test machines; in addition, how to ensure that the test settings and test environment will not cause Additional error is more of a problem

Therefore, testing with analog signals is difficult and expensive

Images