Gadget design, robotics, hacks, DIY technology and more.

This is the schematics for a wireless AM receiver composed of a tuned amplifier, a AM demodulator, and an audio amplifier.

This is the radio receiver implemented on a breadboard.

I’ll post more details soon.

My teammate and I designed an integrated op amp. The circuit is implemented using Gennum GA911 technology. It is built so we can test many configuration (i.e. using active or passive biasing). Se below the circuit layout and some pictures of the resulting chip in it’s natural environment.

Active-loaded differential amplifier. This is the first Stage of the op amp, with a 5o dB Gain.

Class-AB output stage. This second stage alows for driving small loads and increases the overall gain a bit (~10 V/V).

Note: all circuit schematics account for the pin capacitance of the packaged IC (C_pad = 5 pF). Also the loading effect of the oscilloscope probe used to perform the experimental measurements is accounted for in the schematics by modeling the probe as a resistor (R_probe = 1 MΩ) in parallel with a capacitor (C_probe = 15 pF).

IC layout (done using Electric).

The chip (a.k.a. #5) being tested.

The chip in its natural environment.

A close up on the naked chip. Pretty neat.

I’ll post more details soon.