This paper presents a novel technique for measuring the electrical characteristics of analogue circuits, based on measuring the temperature at the silicon surface close to the circuit under test. As a detailed example, the paper analyses how the gain of an amplifier can be observed through temperature measurements. Experimental results validate the feasibility of the technique. Simulated results show how this technique can be used to measure the bandwidth and central frequency of a 2.4GHz low noise amplifier (LNA) designed in a [email protected] standard CMOS technology.