Answers to Quesntions in **broken link removed**
1) If you multiply two pure signals (Cosine or Sine), you get two sum and difference frequencies. Therefore 10KHz * 1KHz, you get 10KHz - 1 KHz = 9KHz, and the other 10KHz + 1KHz = 11KHz. This can is shown in the Table of Complex Identities of any two pure signals, Sine and Sine, Sine and Cosine, Cosine and Cosine. Basically Sine and Cosine are the same, just difference by a 90° phase.
2) ADC suffers from aliasing. Nyquist Sampling Theorem states that the Sampling Frequency should be at least 2 times the maximum frequency at the input of the ADC, i.e. Fsample >= 2Fin or Fsample should be at least 12KHz. For proper reconstruction of the original signal, DAC should also employ Fsample >=2Fin.
3) This is a DC Inverting Amplifier. Using Kirchoff's Current Law, Sum of currents at a point V+ is zero. Vin/R1 = -Vout/R2. Thus the DC Voltage Gain Vout/Vin is -R2/R1 = -3
4) This is a Window Detector, somewhat like a Comparator, such that V+ is (Vout-Vin)*1K/(1K +3K) = (Vout-Vin)/4.
5) This is just a BJT configured with Vin at Base. If load is tapped at Ve, this is described as an Emitter-Follower. The small-signal voltage gain is unity or 1. The phase difference is zero. Ve is one diode drop from Vin. If the load is tapped at Vc, this is the common-emitter collector output stage. The small-signal voltage gain is -R1/R2, thus there is a 180° phase difference between Vout and Vin. Vc is Vcc-Ve-Vce. In both cases, there is no DC gain. However there is a quiescent current of Ve/R2.
6) A simple 2-State CMOS Op-Amp Amplifier. A single-output (between P2 and N3) differential amplifier with a stable current source (by means of a current mirror using P1 and P2) and a biased pull-down resistor (by means of on resistance of a N3). P3 and N4 is a CMOS inverter to serve as the Pull-Pull output stage. This stage is also commonly known as a static driver and it is usually modelled to drive a capacitive load. Since the output of the differential amp is 180°, the inverter compensates this by inverting or adding another 180° to make it 0° or 360°.
7) This is the Back-to-Back Bistable. Older Bistables are made this way as memory device as such a BJT-based Flip-Flop.
8) This is the Wilson's Current Mirror using MOSFETs. Formerly used in BJTs. This kind of Current Mirror increases Linearity by reducing the current programming error of a single current mirror by having another mirror below it.
9) This is the Single-Output Differential Amplifier using BJTs with a simple current mirror as stable current source. However the output experiences a 180° phase difference.
10) Fp is commonly-known as the Maximum Linear Frequency. If Ao is 1, Fp is the Unity-Gain Bandwidth. Fc is the Maximum Operating Frequency or Maximum Bandwidth. This kind of plot is sometimes known as the Bode Plot for analysing Frequency Response of a circuit, a system or a device.