ADC与DAC 衡量指标： 静态指标：DNL, INL; 动态指标：SNR, SINAD, THD ,ENOB, IMD,etc.

动态指标（1） 静态指标反映的特点有限，主要是慢速变化特性，也称之为DC传输特性，对于高速D/A,A/D来说，更需要AC传输特性来表征，反映不同频率信号的响应。 主要反映了D/A, A/D器件的高速工作情况下的性能，诸如，VEDIO DAC, TXDAC， TX ADC等，

动态指标（2） SNR: Signal to Noise Ratio SINAD: Signal to Noise And Distortion Ratio THD: Total Harmonic Distortion ENOB: Effective Number Of Bits SFDR: Spurious-Free Dynamic Range Two-tone IMD……..

Frequency Domain Analysis Fundamental Signal Magnitude Harmonics Spurious H2 H3 H4 H5 Noise Ft (M) Frequency

动态特性的测试方法（1） 对于DAC来说，相对简单一些，通过编程产生单频信号，然后将输出的信号发送到频谱分析仪。

动态特性的测试方法（2） Clock Source Analog Source DUT (ADC) n bits Digital Capture Data Processing (FFT) Sinusoidal Wave Frequency Spectrum

RXADC 测试环境要求（1） Input signal requests： 1：Quality of signal：SNR, THD……. 2：Amplitude , frequency and common voltage of signal . 3：four orthogonal differential signals；

RXADC 测试环境要求（2） How to select sample numbers -----coherent sampling Fin / Fsample = Ncycle / Nrecord, Fin : Periodic input signal Fsample : Sampling frequency of the ADC Ncycle : Integer number of cycles within the sampling window Nrecord : Number of data points in the sampling window or FFT

Coherent sampling

Uncoherent sampling

Windowing

RXADC 测试环境要求（3） 在rxadc的测试中， Fin= Ncycle * Fsample / Nrecord Fin (kHz) Fsamp (kHz) Nrecord Ncycle 10.3819 270.833 600 23 40.1736 89 60.0347 133

RXADC 测试环境要求（4） Spectral leakage sample sequence not meets coherent sampling Windowing minimizes spectral leakage

Window function Window types: Rectangular, Hamming , Hanning, Blackman …… How to select window function: 1: -3dB bandwidth ; 2: -6dB bandwidth 3: maximum side-lobe level 4: side-lobe roll-off rate Blackman windows ----single tone test

Windows function

Windows function

Calculation (1): FFT Ps = sum{Pf(m-k):1:Pf(m+k)}; Pdc = sum{Pf(1:k)}; Ph = sum{Ph(2:n)} ; Ph(i)= sum{Ph(i-1:i+1)}; Pn = sum(Pf) - Ps- Pdc – Ph; Signal bin 的选择：

Calculation (2): FFT S/N = 10* log(Ps/Pn); SINAD = 10* log[Ps/(Pn+Ph)]; THD = 10* log(Ph/Ps); SFDR = 10* log[Ps / Pmax.spurious Level]； ENOB = (SINAD - 1.763)/ 6.02

Signal bin S/N = 10* log(Ps/Pn); ===== = 10*log[10/9]+log(Ps/Pn) = 0.46 + S/N

I/Q match An ideal sinusoidal I/Q signal pair : y(t) =   A exp(i(ωt + φ))   =   A cos(ωt + φ)   +   i A sin(ωt + φ)

I/Q mismatch Amplitude mismatch α and phase mismatch ε : y(t)   =   A cos(ωt + φ)   +   i α A sin(ωt + φ + ε) = 0.5 (1 + α exp(i ε)) A exp(i(ωt + φ))   +   0.5 (1 - α exp(-i ε)) A exp(-i(ωt + φ))

I/Q mismatch calculation Amplitude α=20log(Iamp/Qamp);