# Search results

1. ### Looking for RFIC designer, job located in Changsha, China

Hi all, we are looking for one to two senior RFIC designer, company located in Changsha, China. The requirements are: 1. BSEE or MSEE with at least 3 years' industry experience; 2. Hands on design experience with LNA, mixer, VGA, PA-driver, PLL, VCO, etc. 3. Familiar with RFIC layout; 4...
2. ### How many percent could rise and fall time exist ?

Hi, how many percent could rise and fall time exist in an sampling circuit? Here it is used in the 2 bit AD in GPS circuit. I think that depends on the sampling clock, signal clock and the baseband demodulation requirement. Any formula to caculate this? Thanks!
3. ### how to simulate the Q of active inductor?

For rfic, active inductors using BJT or MOSTs might be used. But how to simulate the Q of active inductor? Thanks!
4. ### How to calculate of the requirements of Op-am when designing a filter?

Hi, How to calculate of the requirement of Op-am when designing a filter? It seems the wrong OP-amp might quite likely to fail the filter. But how could we know what kind of Op-amps do we need? Thanks!

agc gps Hi, I have some questions about AGC and ADC in GPS systems. In GPS systems, 1. how long response time could tbe AGC loop have? 2. should there be a differential-to-single-ended amplifier between AGC and ADC? 3. GPS use BPSK modulation and in the paper "A 19-mW 2.6-mm2 L1/L2...
6. ### Zeroes and Qs, do the theories contrdict?

These 2 things confused me. In the bode plot with poles and zeroes, a zero means an increase in gain and a pole means a decrease in gain. However, in the filters' design, a high Q could cause a ripple, that is, an increase in the gain too. But here no zeroes. So, do the theories contradict? Thanks!
7. ### A P-1db result with a strange plot, why?

I am doing P-1db simulation with Cadence. But the waveform is quite strange with a sudden and sharp decrease in the line. Why dose this happen? This phenomenom happens when some device parameters vary just a little bit! THanks.
8. ### How to flaten the gain variation of a emitter follower?

The output impedance of the emitter follower looks like an inductance. And it would cause a gain variation---a peak in high frequency. Is there anyway to flaten the gain variation caused by this inductance while not affecting its other performance? Thanks Yora
9. ### Why is the noise floor calculated from kT?

The noise floor of a receiver is -174dbm. but why it is caculated from kT instead of 4kT? Thanks!

I have a question when try to estimate a mixer's NF. How dose Cadence spectre calculate the NF of a mixer? I mean, if we are designing a mixer with onchip input from an LNA, then the input impedance of the mixer surely won't be 50Ω. So, when calculate the NF, which needs a value of Rs, dose it...
11. ### Why do we need voltage standing wave ration?

Why do we need voltage standing wave ration or the voltage reflection co-efficient when we just care for the power transport? The maxim power transportation need conjunction impedance matching while the voltage reflection coefficient want the Zs=Zl as long as the Zl could not be treat as a...
12. ### new graduate, wanna find a job on RFIC, I'm in CHina.

I would graduate in 2006 with a master's degree. I have been doing research on RFIC(LNA and Mixer) since I did my thesis for my bachelor's degree. And during my graduate study, I have been respingsible to circuit design and optimization for a low voltage supply mixer with new topology and...
13. ### How to caculate imaginary matrix in Matlab?

imaginary matrix I enter the matrix with i to denote the imaginary part. But it seems that Matlab has ttaken it as a symbol. Ohter symbols were defined. And I read in a book that i is predefined for the imaginary parts. Why can't it work in matrix? And when I caculate a linear matrix, some of...
14. ### Is power gain S21 or (S21)²?

As I know, [S21]² is the power gain. But in some IEEE papers for LNA design, they call S21 the power gain directly. Is there anything wrong?? Thanks.
15. ### Why do we use SFDR instead of using P-1db point?

As I see in books and tech notes, SFDR is not often used and seems mainly for ADC and DAC. Why do people use SFDR instead of P-1db point there? Thanks!
16. ### How to test a dual output mixer??

I am doing a mixer chip. But how to test the low IF output? I choose 20MHz. It seems a bit too low for baluns. How do people test direct conversion mixers? Seems seldom mentioned. Thanks.
17. ### could we make p-cells in virtuso using design rules ?

Some manufacturers offer PDK with p-cells that we could just enter W, L and finger to complete a MOST layout. But when the P-cells are not supplied, could we make it ourselves? That could simple the layout job much. Thanks.
18. ### Induced gate noise VS NQS gate noise current

In staeyert's book it discuss about Non Quasi Static gate noise current. As I read, it's in fact what is called the induced gate noise in other books or papers(the equation is the same.) But as I read in papers, the induced gate noise is not only the Non Quasi Static gate noise. The papers would...
19. ### resouces about GaAs and LDMOS and PHMOS technology

Anyone could tell me where to get the references? Need them to do analysis of failure of chips. Thanks!
20. ### About using 3 MOS modeling the induced gate noise of NMOS

I find this kind of model on standfords website, from **broken link removed** and the model subcircuit is as follows: ** Noisy NMOS model (note: noisy PMOS models is not provided) ************************************************* .subckt NNMOS vd vg vs vb w=1.2u l=0.35u nf=1 sx=1 dx=1 .param...