thin film resistor for TIA

[zappedagain]

I'm looking into changing a transimpedance amplifier (TIA) from a thick film gain resistor to a thin film resistor. I see a thin film resistor shows -20dB on their datasheet (MIL-STD_202 method 308), but I haven't seen this spec on a thick film datasheet. I see MIL-STD-202 has the noise defined as:

"The noise-quality index, expressed in decibels (dB), is a measure of the ratio of the root-mean-square (rms) value of current-noise voltage, in microvolts (μv), to the applied dc voltage, in volts. The pass band associated with the noise-quality index is one frequency decade, geometrically centered at 1,000 hertz (Hz). This index is termed the "microvolts-per-volt-in-a-decade" index."

Anyone know a ballpark for how thick film resistors compare? If it matters, my gain resistor is in the 1 Megohm range.

Z

 

[salmanshu322]

Thin film resistors have a metallic film that is vacuum deposited on an insulating substrate. Thick film resistors are produced by firing a special paste, which is a mixture of glass and metal oxides, onto the substrate. Thin film is more accurate, has a better temperature coefficient and is more stable.