Function generator 8 kHz to 45 MHz – PGEN45

Introduction of PGEN45 modules – linearly controlled rectangular CMOS signal generator in the range of 8 kHz to 45 MHz with the LTC1799 circuit.

Generators are undoubtedly one of the most used elements of our practice. However, it is not always necessary to have a digitally controlled generator with many additional functions. PGEN45 modules represent a simple compromise between parameters and price.

PGEN45 modules, which are based on the LTC1799 integrated circuit, are linearly controlled square wave generators. With the help of two potentiometers, they allow coarse and fine adjustment of the output frequency in the range of approximately 8 kHz to 45 MHz. The output voltage is constant in the entire range of constant 5 Vss.

Img. 1: Module PGEN45 – generator 8 kHz to 45 MHz

Basic properties:

  • Precise rectangular signal generator
  • Adjustable output signal range: 8.3 kHz to 45.5 MHz
  • Frequency deviation less than 1.5% (5 kHz to 20 MHz)
  • Temperature stability: ± 40ppm /°C
  • Output signal: 5 CMOS
  • Output impedance: 100 ohms
  • Output signal rotation: 50% (± 1% for 1 kHz – 2 MHz, ± 5% for 2 MHz – 20 MHz)
  • Supply voltage: 6 – 15 V DC


  • Cheap precision oscillator
  • Generator for SDR receiver
  • Reference power supply for switched power supplies
  • Crystal oscillator replacement
  • Synchronization signal generator
Img. 2: Circuit diagram function generator PGEN45

PGEN45 modules are a simple and easy-to-use CMOS signal source with a level of 5 Vss. The modules are based on the LTC1799 resistor programmable oscillators from Linear Technology.

Img. 3: Internal block diagram of LTC1799

The main advantages of the LTC1799 circuits include their high frequency stability (± 40ppm / ° C), 50% output signal rotation and CMOS level output with an impedance of 100 Ohms. The circuits are designed to generate a signal in the range of 1 kHz to 33 MHz, with a frequency error of less than 1.5% in the range of 5 kHz to 20 MHz.

Img. 4: Parts placement and TOP printing
Img. 5: Parts placement and BOTTOM printing

Furthermore, the PGEN45 modules are equipped with an LDO controller of the LM3480IM3 series, providing a wide range of supply voltages, which can range from 6 to 15 V. The output voltage of the controllers is 5 V, which also defines the output voltage of the generator at 5 Vss.

Measurement results:

Img. 6: Output signal 10 kHz

Img. 7: Output signal 100 kHz

Img. 8: Output signal 1 MHz

Img. 9: Output signal 5 MHz

Img. 10: Output signal 10 MHz

Img. 11: Output signal 20 MHz

Img. 12: Output signal 30 MHz

Img. 13: Output signal 45 MHz

Using a generator:

PGEN45 modules are designed to generate a square wave signal in the range of approximately 8 kHz to 45 MHz. The supply voltage of the modules can be in the range from 6 to 15 V and the level of the output signal is 5 Všš. The output frequency can be set coarsely and finely using two potentiometers.

Img. 14: Basic dimensions and layout of elements on PGEN45 modules
Frequency rangeJumper
8 kHz450 kHz1-2
80 kHz4.5 MHz
800 kHz45 MHz2-3

To use PGEN45 modules, all you have to do is connect a supply voltage between 6 and 15 V and set the required output frequency using two potentiometers.

signal generator
Img. 15: Module PGEN45 – TOP
function generator
Img. 16: Module PGEN45 – BOTTOM

Links & downloads:

LTC1799 – 1kHz to 33MHz Resistor Set SOT-23 Oscillator

Original link:

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