While on a hunt for a killer prior art, even after putting in a lot of time, it is not certain that you will get a promising reference. One of the many reasons could be that while conducting a prior art search, although we concentrate on all major key assignee’s or inventors, sometimes we might overlook the art from the same inventor or assignee with the conviction that it would only cover the general background.

Let me narrate an experience where we found a promising reference belonging to the same assignee as the subject patent. This case was a strength-check test to assess the validity of a patent.

Patent Understanding: The First Step of Prior Art Search

The patent was related to an amplifier apparatus having a low-noise amplifier (LNA) and having a selectable gain. Further, the output of LNA was coupled with a switchable gain buffer wherein, the switchable gain buffer comprises selectable gain channels as shown in figure 1. Also, the selectable gain channels comprised of transistors.

After understanding the patent, we analyzed the prosecution history to understand the novel elements, existing prior-art cited by the applicant and examiner. We also noted the key inventors and assignees.

Strategies To Proceed With The Search

As usual, we first started with keyword-based search, however, we came across a lot of patent art. It was strenuous for us to analyze such huge art. We tried to restrict these keyword-based strings by applying classes, however, we did not locate any useful reference.

We thought of performing an assignee-based search. We searched for all potential assignees along with the assignee of the subject patent. We noted that the assignee of the patent had done most of the work in this field. So, without wasting much time, we began with the analysis of the assignee’s portfolio related to low noise amplifiers.

Reference Identified

Bingo! We came across a promising art from the same assignee which was published a few years before the priority date of the subject patent. This reference had inventors different from those of subject patent.

The reference discloses a signal amplified by a low noise amplifier (LNA) wherein, the output of LNA is coupled with VGA as shown in figure 2.

Further, figure 3 shows an amplifier and it was given in the reference that this amplifier can be used for LNA. When we looked at the amplifier, we came to know that it includes a plurality of selectable amplifier gains coupled in parallel.

As in the subject patent, the output of LNA is coupled with the switchable gain buffer that comprises selectable gain channels. Similarly, in the reference, we identified the output of LNA is coupled with VGA. Further, it was written that the same amplifier shown in figure 3 can also be used for VGA.

So we again analyzed that amplifier and observed that the amplifier includes a plurality of amplifier stages (i.e. selectable gain channels) coupled in parallel as shown in figure 4. Also, these selectable gain channels comprised of transistors.