Linear Technology AN85-1 Low Noise Varactor Biasing Application Note

This document describes the biasing considerations for the varactor diode required for tuning high frequency oscillators, and provides a low noise varactor biasing method.

Brand: Linear Technology
Category: Other Electronics
Document type: Application Note
Language: English
Pages: 24
File format: PDF
File size: 479 KB
Published: 05 June, 2012
Updated: 28 September, 2023
MD5 checksum: 3B3EAA44674F77ED48D867C7B200E089
PDF: Linear Technology AN85-1 Low Noise Varactor Biasing Application Note PDF

About this manual

Telecommunication and satellite links require tuning high frequency oscillators using varactor diodes. These devices need a wide voltage swing (0.1V to 30V) for operation, which complicates biasing in low-voltage systems that rely on switching regulators due to potential noise interference.

What's inside

Introduction
Varactor Biasing Considerations
Low Noise Switching Regulator Design
Layout Issues
Level Shifts
Test Circuit
Noise Performance

Frequently asked questions

What is the switching frequency of the LT1613 used in this design?

The LT1613 has a 1.7MHz switching frequency.

What is the required voltage swing for varactor operation?

A 0.1V to 30V swing is required to achieve a 10:1 capacitance shift.

What components are recommended for the capacitor C2 in Figure 3?

The Murata GRM235Y5V475250 is specified for component C2.

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