A high-performance self-detection external reference time base circuit and its realization method

Abstract

The invention discloses a high-performance self-detection external reference time base circuit and its realization method, comprising: an external reference filter amplifier circuit connected in series, an external reference self-detection circuit, an external reference phase detection filter circuit, a two-choice switch and constant temperature crystal oscillator; the output terminal of the external reference self-detection circuit is connected to the selection control terminal of the one-of-two switch; the output terminal of the external reference phase detection filter circuit is connected to one of the input terminals of the one-two switch; when the external reference signal is input, the external The reference filter amplifying circuit divides the external reference signal into two circuits after filtering and amplifying, one of which is connected to the external reference phase detection filter circuit, and the other is connected to the external reference self-detection circuit, and controls the switch to switch to the output of the external reference phase detection filter circuit The terminal makes the external reference signal loop phase locked. The beneficial effects of the present invention are: even if there is an external reference signal input, the whole machine can also choose whether to use the external reference signal through FPGA control.

Description

technical field [0001] The invention relates to the technical field of measuring instrument circuits, in particular to a high-performance self-detection external reference time base circuit and a realization method thereof. Background technique [0002] In the use of various test instruments, the external reference time base circuit and the controllable reference source generating circuit are necessary circuits for the measuring instrument. Therefore, the intelligence and flexibility of the circuit have a great influence on the measurement accuracy and practicability of the measuring instrument. [0003] The current external reference time base circuit is mainly realized in the following ways: [0004] The traditional external reference time base circuit is generated in the following way: through the host computer to control a switch to select the internal reference clock or external reference clock for the whole machine, when the switch selects the internal reference clock...

AI Technical Summary

Problems solved by technology

[0009] First: In the external reference time base circuit, the upper computer can only switch between the external reference and internal reference signals by controlling the one-of-two switch. Even if it is switched to the external reference signal input state, it cannot directly judge whether the external reference signal is input.

[0010] Second: A high-performance constant temperature crystal oscillator and voltage-controlled oscillator are required in the entire circuit, and the cost of the circuit is relatively high

[0011] Third: In the reference source generation circuit, the upper computer cannot achieve the generation control of the reference source signal through simple control

Images