公开(公告)号：US5012244A

公开(公告)日：1991-04-30

申请号：US429214

申请日：1989-10-27

Applicant: David R. Wellard ,  Donald A. Kerth ,  Bruce P. Del Signore ,  Eric J. Swanson

Inventor： David R. Wellard ,  Donald A. Kerth ,  Bruce P. Del Signore ,  Eric J. Swanson

IPC: H03M3/02

CPC classification number: H03M3/364 ,  H03M3/43 ,  H03M3/448 ,  H03M3/452

Abstract: An oscillation detect and reset circuit is provided for an analog modulator that includes a first stage of integration having a single ended differential amplifier (32) which is connected to the input of three stages of subsequent integration (40), (42) and (44), in a cascaded configuration. The output of the last stage of integration (44) is connected to the input of a one-bit quantizer (48). The output of the one-bit quantizer (48) is connected to the input of a current (50) feedback, which is connected between a summing node (36) and a negative voltage supply. The summing node (36) sums the current feedback with an input voltage for input to the amplifier (32). Switches (52), (54) and (56) are provided across the inputs and outputs of the integration stages (40), (42) and (44), respectively. The sensing of an unstable condition on the output of second stage of integration (40) is detected by oscillation detect comparators (60) and (62) to initiate a count cycle in a five-bit counter (66). The output of counter (66) generates a oscillation detect signal upon detection of an oscillation, which signal is output to the control inputs of the switches (52), (54) and (56), for thirty-two cycles of the analog modulator sampling frequency. This is a sufficient amount of time to allow the loop, which is a first order loop, to zero out during the reset period.

Abstract translation: 提供了一种用于模拟调制器的振荡检测和复位电路，该模拟调制器包括具有单端差分放大器（32）的第一级积分，该单端差分放大器连接到三级后续积分（40），（42）和（44 ），在级联配置中。 最后一级积分（44）的输出端连接到一位量化器（48）的输入端。 一比特量化器（48）的输出连接到连接在求和节点（36）和负电压源之间的电流（50）反馈的输入。 求和节点（36）将电流反馈与用于输入到放大器（32）的输入电压相加。 分别在积分级（40），（42）和（44）的输入和输出两端提供开关（52），（54）和（56）。 通过振荡检测比较器（60）和（62）检测第二级积分（40）输出的不稳定状态，以启动五位计数器（66）中的计数周期。 计数器（66）的输出在检测到振荡时产生振荡检测信号，该信号在模拟调制器（52），（54）和（56）的控制输入端输出三十二个周期 采样频率。 这是足够的时间来允许在复位周期期间循环（这是第一阶循环）为零。