Some stocks may make you want to wash your hands after hitting the "buy" button, even if you're making money. The opposite of these "sin stocks," on the other hand, leave you feeling good about your investment's impact on the world at large. Socially responsible investing can fill your pocketbook and let you sleep at night.

Image source: Broadcom.

Semiconductor designer Broadcom (UNKNOWN:BRCM.DL) has passed a strict screening process by financial analyst firm Calvert Investments, and is now included in the prestigious Calvert Social Index list of corporate altruists. Many socially responsible investing funds are based directly on this index, making Broadcom a popular holding for investors with a conscience -- whether they're aware of Broadcom's presence or not.

Broadcom is unquestionably a socially responsible investment: Calvert requires any company to pass all seven of the index's core criteria before issuing this honor. That means caring for the environment, respecting human rights, producing safe products via safe processes, showing strong corporate governance policies, and much more.

So owning Broadcom stock passes as a socially responsible investment. But can Broadcom shares boost your retirement portfolio, too?

What the pros are saying
The stock is getting some respect from Wall Street pros right now. Broadcom shares jumped more than 3% on Thursday as Goldman Sachs analyst Mark Delaney upgraded the stock to a buy.

Delaney stuck a $48 price target on Broadcom, leaving plenty of room for further gains if his thesis plays out. That thesis focused on the expected lift from Broadcom's upcoming analyst day, which has tended to boost share prices in the past.

More to the point, Delaney wants to hear Broadcom's management talk about margin expansion and positive product cycles. Video encoding chips for 4K video devices should help Broadcom grow its broadband communications division in coming years, while connected devices (read: the Internet of Things) provide a similar boost for the mobile and infrastructure segments.

Broadcom investors already knew these things
The Goldman analyst's comments should not surprise Broadcom investors, since they were in line with management's discussion of the company's recently reported third-quarter results.

Broadcom CEO Scott McGregor is taking the company in a new direction. Image source: Broadcom.

On a longer timeline, Broadcom is revamping its overall business mix. The company is closing out its wireless baseband products line, with has become a low-margin drag on earnings. In that impressive third quarter, this segment delivered higher sales than expected. Hence, Broadcom beat Wall Street's revenue targets but missed its earnings estimates.

But, since Broadcom had a perfectly reasonable explanation for that earnings miss and it actually serves as a sign of better things to come, the stock rose on that report anyhow.

The big bounce
Broadcom shares have soared 42% year to date to crush the market, bouncing back from a terrible second half of 2013. The re-imagined business mix looks like exactly the right medicine for what ailed Broadcom last year.

Investors shouldn't expect another year of 40% returns out of Broadcom, though.

The rebound from last year's baseband-fueled issues has already played out, and the stock isn't exactly cheap today. If the stock rises to match Goldman's $48 target, investors would see a 14% gain -- nice, but hardly game changing. And right now, Broadcom stock trades for 58 times trailing earnings. That's not exactly a deep-discount bargain.

The final verdict
This is a stock and a business on the rebound from darker days. Broadcom investors might have already grabbed most of their low-hanging fruit, but the company is set up to follow new market trends like the Internet of Things revolution from a stable platform.

Paired with a top-notch social responsibility scorecard, Broadcom looks like one of those stocks you can buy now, own for decades, and never lose a minute of sleep over it.