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Design >> RF Design >> Core transistor used in VCO?
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Message started by wafer_instructor on Aug 27^th, 2019, 12:15am

Title: Core transistor used in VCO?
Post by wafer_instructor on Aug 27^th, 2019, 12:15am

Hi,

We have many choices in a technology for transistors. They are seperated by maximum applied voltages. For example, in TSMC65nm transistors are characterized by "Nominal Supply Voltage" and it corresponds to Vdd. In transient operation, Peak voltage swing can reach 2 time Vdd value for RF circuşts with inductors. At this point, I think peak voltage swing must stay below "Nominal Supply Voltage" value. So, if you have high voltage swing circuit like voltage controlled oscillator (VCO), you must choose high voltage one. Nominal supply voltage is 1.2V and transient voltage reaches 1.9V. My question is that:
Can I use core transistor in a VCO with voltage swing above "Nominal Supply Voltage"?
RF core transistor or Digital Core Transistor can be used? :)

Title: Re: Core transistor used in VCO?
Post by subtr on Sep 13^th, 2019, 6:26am

The transistor does not know anything about whether it's sitting in a VCO or not. It will break down if it sees voltages above reliability limits. But then if you re design your VCO with both PMOS and NMOS, the swing can be limited.