Unlock instant, AI-driven research and patent intelligence for your innovation.

A PLL Low-pass Filter Based on Transconductance Operational Amplifier

A technology of operational amplifiers and low-pass filters, applied in the field of phase-locked loop low-pass filters, can solve the problems of large capacitor array chip area, insufficient stability, and inability to linearly adjust the resistance and capacitance of the access circuit, and achieve bandwidth Constant, small chip area effect

Active Publication Date: 2018-02-06
SOUTH CHINA UNIV OF TECH
View PDF6 Cites 0 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this structure has two disadvantages. The first is that the chip area occupied by the capacitor array is relatively large; Big difficulty, it is not easy to keep the bandwidth of the loop constant when the gain of the voltage-controlled oscillator changes or the frequency division ratio of the frequency divider changes, and it is not stable enough

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • A PLL Low-pass Filter Based on Transconductance Operational Amplifier
  • A PLL Low-pass Filter Based on Transconductance Operational Amplifier
  • A PLL Low-pass Filter Based on Transconductance Operational Amplifier

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0047] This embodiment describes in detail the working principle of the phase-locked loop low-pass filter of the present invention.

[0048] From figure 1 and Figure 4 It can be learned that figure 1 The open-loop transfer function H in open (s) are:

[0049]

[0050] Among them, Z lpf (s) is the transfer function of the loop filter, is the transfer function of the charge pump, is the transfer function of the voltage control device, and N is the frequency division ratio of the frequency divider.

[0051] From Figure 4 The loop filter circuit in can be known as:

[0052]

[0053] Then the open-loop transfer function H open (s) become:

[0054]

[0055] Transforming this transfer function gives:

[0056]

[0057] Below to Figure 7 Taking the application example of the present invention as an example, the open-loop transfer function of the application example system is deduced. Figure 7 The open-loop transfer function H of the application example sy...

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

PUM

No PUM Login to View More

Abstract

The invention discloses a phase-locked loop low-pass filter based on a transconductance operational amplifier, comprising a first transconductance operational amplifier, a second transconductance operational amplifier, a third transconductance operational amplifier, a fourth transconductance operational amplifier, a A capacitor and a second capacitor. The invention adopts 4 transconductance operational amplifiers based on MOS technology and 2 capacitors to realize the low-pass filter, no capacitor array is needed, and the occupied chip area is small; no need to adjust the resistance value and capacitance value of the access circuit To change the bandwidth of the loop, the bandwidth of the loop can be linearly adjusted only by linearly changing the transconductance values ​​of the four transconductance operational amplifiers. Keep the bandwidth of the loop constant when changing, which is more stable. The invention can be widely used in the field of integrated circuits.

Description

technical field [0001] The invention relates to the field of integrated circuits, in particular to a phase-locked loop low-pass filter based on a transconductance operational amplifier. Background technique [0002] PLL (Phase-Locked Loop, phase-locked loop) circuit is a system that uses feedback technology to compare the input phase with the output phase to obtain a stable output signal. It is widely used in electronic information systems. [0003] Charge-pump phase-locked loops are widely used in modern wireless communications. figure 1 It is a structural block diagram of a charge pump phase-locked loop in the prior art, including a phase frequency detector (PFD), a charge pump (CP), a loop filter (LPF), a voltage controlled oscillator (VCO), a frequency divider ( Divider). Among them, the frequency and phase detector compares the input reference signal f ref and the feedback signal f div , output the Up signal and Down signal including the phase difference. The char...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

Application Information

Patent Timeline
no application Login to View More
Patent Type & Authority Patents(China)
IPC IPC(8): H03L7/093H03L7/18
Inventor 吴朝晖涂玮王昆赵明剑李斌
Owner SOUTH CHINA UNIV OF TECH