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正交检波器可用来解调频移键控和其他类型的FM信号.图1所示的MC13156是一个FM子系统集成电路,它在正交检波器之前把RF下变频到10.7MHz中频(IF)、并进行放大和限幅.在MC13156内的正交电路依靠连接到脚13的外部振荡回路.此振荡回路由150pF电容器和1.5μH电感器组成.它必须可靠地调谐到10.7MHz,而且在完全规定的温度范围内决不能偏离中心频率.图1中的TL072运放是—个外部数据限制器的一部分,在MC13156的脚14处为解调数据提供电流源输出.
The quadrature detector can be used to demodulate frequency shift keying and other types of FM signals. The MC13156 shown in Figure 1 is an FM subsystem integrated circuit that downconverts RF to a 10.7MHz IF before the quadrature detector. , And amplified and limited. The quadrature circuit in the MC13156 relies on an external tank connected to pin 13. The tank consists of a 150-pF capacitor and a 1.5-μH inductor. It must be reliably tuned to 10.7 MHz, The specified temperature range must never deviate from the center frequency. The TL072 op amp in Figure 1 is part of an external data limiter and provides a current source output for demodulated data at pin 14 of the MC13156.