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5. SOURCES OF ERRORS. 5.4. Low-noise design: noise matching. 5.4.1. Optimum source resistance

5. SOURCES OF ERRORS. 5.4. Low-noise design: noise matching. 5.4.1. Optimum source resistance. 5.4. Low-noise design: noise matching. 5.4.1. Optimum source resistance. The. 100. R s for maximum SNR. 10. V in = e n ·1 Hz 0.5. 1. R s for minimum F.  4 kTR s B. 0.1. 20.

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5. SOURCES OF ERRORS. 5.4. Low-noise design: noise matching. 5.4.1. Optimum source resistance

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  1. 5. SOURCES OF ERRORS. 5.4. Low-noise design: noise matching. 5.4.1. Optimum source resistance 5.4. Low-noise design: noise matching 5.4.1. Optimum source resistance The.

  2. 100 Rs for maximum SNR 10 Vin = en·1 Hz0.5 1 Rs for minimum F 4kTRsB 0.1 20 100 101 102 103 104 15 SNR0.5 F0.5 10 5 0 100 101 102 103 104 5. SOURCES OF ERRORS. 5.4. Low-noise design: noise matching. 5.4.1. Optimum source resistance Example: Noise factor and SNR as a function of Rs en = 2 nV/Hz0.5, in = 20 pA /Hz0.5 vn in rms = [4kTRs + en rms2 + (in rmsRs)2]0.5 in Rs vn in rms, nV/Hz0.5 en 1 0.8 0.6 0.4 0.2 0 Rs, W

  3. en en in in n2Rs Vmsr Vo nVin AV RL 5. SOURCES OF ERRORS. 5.4. Low-noise design: noise matching. 5.4.1. Optimum source resistance A.Transformer matching with an1:n turns ratio Measurement object Measurement system Rs Vmsr Vo 1:n Vin AV RL n2Rs nVin Measurement object Measurement system

  4. 100 Vin n= nen·1 Hz0.5 10 1 4kTRsB 10 0.1 100 101 102 103 104 8 F0.5 SNR0.5 6 4 2 100 101 102 103 104 5. SOURCES OF ERRORS. 5.4. Low-noise design: noise matching. 5.4.1. Optimum source resistance Example: Optimum source resistance Rs=1 W, en = 2 nV/Hz0.5, in = 20 pA /Hz0.5 Rs 1:n Vin in Rs vn in rms, nV/Hz0.5 en Rs n2 Vin n Thermal noise in Rs Rs n2, W

  5. en en in in 5. SOURCES OF ERRORS. 5.4. Low-noise design: noise matching. 5.4.1. Optimum source resistance B.Transformer coupling with ann:1 turns ratio Measurement object Measurement system Rs Vmsr Vo n:1 Vin AV RL Rs /n2 Vin /n Measurement object Measurement system Rs /n2 Vmsr Vo Vin /n AV RL

  6. 100 10 1 4kTRsB n2Rs, W 0.1 100 101 102 103 104 100 101 102 103 104 5. SOURCES OF ERRORS. 5.4. Low-noise design: noise matching. 5.4.1. Optimum source resistance Home exercise: Optimize noise factor and SNR Rs=200 W, en = 2 nV/Hz0.5, in = 20 pA /Hz0.5 Rs n:1 Vin in Rs vn in rms, nV/Hz0.5 Rs /n2 Vin /n en Thermal noise in Rs ? SNR0.5 F0.5 Rs /n2, W

  7. 5. SOURCES OF ERRORS. 5.4. Low-noise design: noise matching. 5.4.1. Optimum source resistance C.Parallel connection of input stages

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