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

Back-proch clamp circuit

A clamping and level technology, applied in the direction of TV, electrical components, color TV, etc., can solve the problems of difficult loop response stability, difficult to identify trailing edge interval, long loop initial stability, etc.

Inactive Publication Date: 2004-02-11
THOMSON LICENSING SA
View PDF0 Cites 1 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Second, the loop gain is determined by the inverse of the sum of resistors 32 and 36, so the lower
Third, loop response stability is difficult to achieve when using two dominant poles associated with input capacitor 8 and filter capacitor 34, and when A / D converter 12 and VDEC 14 begin to exceed their optimal dynamic Outside the range, the initial settling of the loop is too long due to the difficulty in identifying the trailing edge interval

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
  • Back-proch clamp circuit
  • Back-proch clamp circuit
  • Back-proch clamp circuit

Examples

Experimental program
Comparison scheme
Effect test

Embodiment Construction

[0011] The characteristics and advantages of the present invention will become clearer from the following description through examples.

[0012] See image 3 , Shows a typical sync pulse top clamp circuit 40, used in conjunction with a video input to a video processing unit such as Broadcom 7020 IC. The transistor 42, the transistor-based circuit, namely the resistor 44, the resistor 46 and the capacitor 34, and the emitter resistor 48 provide a fixed DC voltage. The clamping operation is performed by the diode 50, the leakage resistor 52, and the coupling capacitor 8. The voltage to which the top of the sync pulse will be clamped is determined by the division ratio of resistors 44 and 46.

[0013] See now Figure 4 When the PWM signal 30 is applied to the sync pulse top clamp circuit reference input 33 through the resistor 32, the PWM output 30 will be low-pass filtered by the capacitor 34 and will provide a variable reference to the sync pulse top clamp circuit. In this way, in r...

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 teaches a method, means and apparatus for clamping a back porch interval of a video signal including clamping a sync-tip level of said video signal to a variable reference voltage (33), comparing a back-porch voltage level of the sync-tip clamped video signal to a predetermined reference voltage (22), generating an error signal (24) representative of the difference between the back-porch voltage level and the predetermined reference voltage (22), and adjusting the variable reference voltage (33) in response to the error signal (24) such that the error signal (24) is minimized.

Description

Technical field [0001] The present invention relates to video signal processing. Background technique [0002] In a video signal processing system, whether it is purely analog or digital video, it is often desirable to implement a trailing edge clamp circuit to set the DC operating point of the signal to a predetermined reference voltage. In order to understand the traditional technology, we will explain figure 1 The recommended operation of Broadcom 7020IC 10 is shown in. The video signal V1 is buffered by the video operational amplifier 6, and is provided to the video input terminal of the IC 10 through the coupling capacitor 8, wherein the video signal is digitized by the analog-to-digital (A / D) converter 12 and applied to the video decoder in parallel The input 16 of the comparator (VDEC) 14 and the keyed comparator 18. The other comparator input 20 receives a predetermined reference voltage 22. The comparator output 24 is an error signal, which outputs the difference betwee...

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 Applications(China)
IPC IPC(8): H03M1/12H04N5/18
CPCH04N5/185H04N5/18H03M1/1295
Inventor 罗纳德·T·基恩
Owner THOMSON LICENSING SA