I like to protect a sensitive circuit of mine with a shield. I don't have a picture but basically, I have put together a 1mm thick ground rectangle on top layer and I will place the shield on top of this such that it will contact to this ground trace.

I have some concerns.

1. am I creating a ground loop by doing this?
2. If I don't use the shield, am I making an antenna that will pick up noise?
3. What is the recommended practice for this type of shield?

Actually, I like to connect the shield at a single point but a hardware person who has more experience insists that he like to have a full rectangular ground exposes so that shield can touch to the ground at every point.

Experts, please weigh in.

Update

Here is a very rudimentary representation.

UPDATE 2

Noise is at the output of our amplifier. (Transimpedance) It is around 3-5mV for an amplification of 300K. (I have made mistakes int eh first layout, now doing a better board and the goal is to reduce the first stage noise less than 1mV)

I have two ldo's that take energy from battery. Both of them high PSRR. This is a 6 layer board with the following stack up S/G/S/G/P/S. This is a bit unusual but stack up but I hide sensitive signals between these grounds. The board doesn't need to be 6 layer but this later will become part of another crowded board hence the 6 layers.

Noise sources are in abundance:

• Power supply: We mitigate this with good LDOs and filtering (pi filter) and bypass etc. caps. So far, worst case I see 1-2mV ripple on power, this could even be my equipment. (I don't have good equipment, also I the amplifiers has 50+dB PSRR, so this should have minimal impact on the output)

• Opamp noise: This is the inhering noise coming from the amplifier. I have a low noise Opamp. \$3 nV/\sqrt{Hz}\$.

• Photodiode: I use a large photodiode, this picks up noise, unavoidable.

• Other electromagnetic sources: We have seen the board is very sensitive, the noise goes up in various situations. Also, the reference schematics from some sources recommend shielding the reduce outside noise sources, so we are putting this shield option to test our next board.